Based on this pattern of results, for both racial/ethnic groups and substances, we proceeded with a model that allowed for A and E and combined the sources of familial environment (C+T; broad family environment) into a single parameter (Table 3). Using this model, we noted that, for each substance, while either A or C+T could be equated across racial/ethnic groups, the total extent of familial variance (A+C+T) was substantially greater in EA relative to AA women (i.e., for cigarettes: 54% in AA vs. 89% in EA; for cannabis: 58% in AA vs. 81% in EA). Consequently, the role of individual-specific environment was significantly less pronounced in EA women, particularly for cigarette use. Sensitivity analyses revealed that estimates of E for cigarette use in AA women might be 2.15 to 7.35 times greater than those for their EA counterparts (Supplemental Figure 12), and that for cannabis use, the E in AA women might be 1.10 to 3.70 times greater than the EA estimate (Supplemental Figure 23).
